1. Field of the Invention
This invention relates to personal computer systems, and more particularly to computer expansion slot adapters for providing additional connections to data devices.
2. Description of the Related Art
A typical personal computer is constructed with a system board that includes the various elements comprising the primary digital electronics necessary for the processing functions of the computer. The digital electronics are electrically connected to a common data bus on the system board. Data devices such as video monitors and data storage devices may also be connected to the computer data bus. The storage devices include hard disk drives, floppy disk drives, optical compact disc (CD-ROM) devices, and magnetic tape drives. Each data device typically includes a cable projecting from the device cabinet and a controller circuit board within the cabinet connected to the cable and provided with a multiple-pin connector. Several multiple-pin connector sockets, or expansion slots, are provided on the system board for connection with the device circuit board. A data device is connected to the data bus by mounting the circuit board in one of the expansion slots and connecting the device cable to the circuit board.
The system board expansion slots are electrically connected to the data bus. When a data device is connected to an expansion slot, data from the device is passed along the cable to the device circuit board, the data bus, the computer digital electronics, and other data devices. That is, when data is passed from one peripheral device to another, or to the digital electronics of the computer, the data is passed along the data bus.
Generally, one expansion slot is required for each data device. Some personal computers are provided with up to eight expansion slots. Other computers may have more limited expansion slot capabilities. For example, the IBM "PS/2" computer has only three.
Many users want to connect a large number of devices, such as additional monitors, storage devices, and the like. Other devices that are fast becoming popular, such as optical character readers, modems, and interfaces to other computer systems, also require expansion slots. All of these devices are competing for the fixed number of expansion slots on a personal computer. Thus, there is often a need for connecting a data storage device with a personal computer without decreasing the number of expansion slots available for other devices.
Each personal computer operates in accordance with a particular data interface standard. For example, the current interface standards that are in most widespread use are known as the ST-506, ESDI, SCSI, and AT interface standards. These standards prescribe the number of data lines to be used, the sequence and protocol for data transfers, timing requirements, interrupt signals, and other technical specifications for data transfer. The transfer of data between the computer and the devices is accomplished in accordance with the interface standard under the control of the basic input/output system (BIOS) of the computer. The BIOS allows the personal computer to communicate with the data device. The data storage device that will be connected to the personal computer must include a device controller having a BIOS that will be compatible with the BIOS of the personal computer. The device controller typically comprises a circuit board upon which digital electronic components are mounted. The circuit board includes electrical pin connectors that are inserted into one of the expansion slots of the system board. Thus, the device controller uses up another one of the expansion slots of the system board. There is a need, therefore, for a device controller that does not use up one of the expansion slots, leaving them free for other devices.
Another important feature of the personal computer is its ability to be part of a network of computers, or a local area network ("LAN") system. The computers in a network can share information and tasks. LAN systems include a network circuit board that is connected to an expansion slot on the computer system board, thus using up yet another one of the expansion slots. There is a need for a network interface for a LAN system package that provides compatibility with a LAN system but that does not require a LAN network board connected to an expansion slot of the computer.